Geothermal Energy, Plate Tectonics, Volcanoes, and Earthquakes

Geothermal Energy and Plate Tectonics

Geothermal energy is the internal heat of our planet. It significantly impacts Earth, originating from the planet's formation process and the radiation emitted by the decay of radioactive elements (uranium, thorium, potassium).

This internal heat drives continental drift, volcanoes, earthquakes, the origin of ridges, the formation of some rock types, and their deformations.

Continental Drift

Millions of years ago, the continents were joined together as a supercontinent called Pangea. Wegener provided evidence for this but could not explain the force that moved those land masses. Several factors support the theory of continental drift:

• Geographical reasons: The coastlines of some continents fit together (e.g., coastal South America with West Africa).
• Climatic reasons: There are remains of glaciers in Brazil and the Congo, and coal deposits in Greenland. This suggests that these areas were in different locations in the past.
• Biological reasons: On either side of the Atlantic, there are animals of the same species that cannot swim.
• Paleontological reasons: Fossils of animals and plants appear on both coasts of the Atlantic.

At 60, after Wegener's death, researchers completed his theory, which was called plate tectonics. It states that the lithosphere is not continuous but is divided into lithospheric plates.

Types of Lithospheric Plates

• Oceanic plates: Composed of oceanic lithosphere.
• Continental plates: Composed of continental lithosphere.
• Mixed plates: Composed of both continental and oceanic lithosphere.

Convection Currents

Convection currents are cycles of movement of mantle materials. They cause the displacement of the plates. There are several types of plate interactions:

• When two plates move apart, it causes dorsals.
• When two plates collide, one slides under the other, causing earthquakes, volcanoes, and mountain ranges.
• When the plates slide relative to one another, it causes earthquakes.

Volcanoes

A volcano is a crack where hot material from inside the Earth is expelled.

Volcanic Products

• Liquids: Molten lava at 1000ºC.
• Gases: Magma, a molten mixture of minerals, water, and solid rock fragments.

Types of Volcanic Eruptions

• Hawaiian Volcano: Very fluid magma, gas leaks, and almost no explosions.
• Strombolian Eruption: Less fluid magma, gas explosions, and moderate lava flows.
• Pelean Eruption: Very viscous magma; gases cause an explosion with difficulty escaping.

Volcanic Hazards and Prediction

Volcanoes emit lava, gases, pyroclastics, ash rain, and raging clouds, potentially burning cities and causing flooding due to melting caused by the volcano's heat.

Volcanic Prediction: Includes the appearance of cracks where gases exit, a rise in groundwater temperature, earthquakes, elevation of the land, and nervous animal behavior.

Volcanic Prevention: Involves plans for the population, civil protection programs, and dams to slow or divert lava.

Earthquakes

An earthquake is a jerky movement of the Earth that releases a large amount of energy.

Parts of an Earthquake

• Hypocenter: The place of origin of the earthquake and, therefore, the seismic waves.
• Epicenter: The place on the Earth's surface where the effects of the earthquake are first and most strongly felt.
• Seismic Waves: Vibrations of the earthquake.

Earthquake Consequences and Mitigation

Causes: Collapse of buildings, destruction of cities or towns, fires, and floods due to the destruction of dams.

Prediction: Tremors of the Earth's surface, inclination of the Earth, changes in the magnetic field, variations in water level, and nervous behavior of animals.

Prevention: Risk maps, seismic-resistant buildings, civil protection programs, and keeping people informed.